Three questions in one... Rear end.

[toofun]

So I figured instead of listing three separate questions I would lump them all into one since they all have to do with the rear of the car.

I have a 68 camaro with a 9 inch rear Question 1.. The angle of the tranny is -5 degrees, the measurement of the driveshaft approx 3/4 of the way down is -3 degrees and lastly the measurement of the pinion yoke on the 9 inch is right as 0... Is this correct? I get horrible wheel hop and am running DSE 3 inch leafs with non staggered bilstein shocks.. Problem becomes if I have to change that pinion angle I dont see how I can since the DSE collars are already WELDED to the tubs of the axle.

Question 2.. I have been debating going with a 4 link but want to retain as much of the 9 inch as I can ( I may buy a new housing to make install easier) The axles I have dont look stock and have a large M raised on them with the number +53 on it. Someone told me that they are Moser axles which I hope is the case..

Question 3.. The car makes a horrible clicking almost sound only when I am going around turns slowely.. The rear is real squirrely and I do want to go with a 4 link but I dont know what to keep or not to keep of the 9 inch.. This car originally was setup for the drags (from what I can tell by the wheels, long half inch studs, tires, cage, fuel cell, etc.. so I am assuming that maybe this guy went with a drag setup? The car makes unbelievable power but I just cant seem to keep the rear end under control.. Downright scary.. I also believe he went with c clip eliminators which Moser states is a NO NO for the street and should only be used for drap racing straight line applications due to the fact that they will crack on turns and leak.

Thanks in advance!

Mark
TOOFUN

[Bryce]

1. you have a working angle of 2* in the front and 3* in the back. That is okay. If you use tapered shims between the leaf springs and the axle pads then you can change the pinion angle. If the DSE springs have a stiffer front half of the spring then you will have less wheel hop.

2. Most 4links will clamp onto the leaf pads or weld on new brackets. You can probably modify your housing.

3. You have a detroit locker. I have never heard that you cannot use c-clip eliminaters on the street. 9" fords do not use c-clips they use axle retainers bolted to the housing ends.

[exwestracer]

IF you're looking for a second opinion...

1) The 0deg pinion angle is higher than we normally use on a performance leaf spring setup. Rather than messing around trying to get the pinion angle down, I would add a pair of properly located upper radius rods to control axle wrap. Yes, it's old technology, but simple, cheap and it still works. Nothing wrong with converting to a 4 link, but unless you have some other good reason, the leafs sould work fine.

2) It will end up being a major project if done correctly. Bryce is right in that you shouldn't have to cut the housing, but the chassis is another story.

3) Yup, Detroit Locker; and yup, no c-clip eliminators on a 9" Ford. You sure sombody didn't sneak an 8.8 under there? Does it have a bolt on back cover over the gear?

[Bryce]

1) If you are drag racing or just accelerating and your A/S is great than 100% then I would want the pinion pointing down. The pinion angle will have a dynamic change under acceleration and will be point up. To prevent a huge a working angle between the driveshaft and pinion it is best to bias the pinion down.

[davidk68]

Isn't the pinion angle usually pointing up and the engine pointing down. And shouldn't they usually be equal (or close) and opposite?? Say 2 degrees down for the engine and 2 degrees up for the pinion??

David

[toofun]

OK so heres what I know so far.. I definately have Moser axles and I would venture to say that I definatley have a detroit locker differential in the rear.. When I was reading up on them it says that power is always 100% put to both wheels all the time and that the unit "ratchets" around corners(which sounds exactly like what the car is doing) The car really launches extremely hard off the line but the rear gets real squirrely when getting on and off the throttle which again I hear is common with this type of differential(unless Im wrong). So maybe its not wheel hop but that "loose" feeling I get in the rear of the car that throws me..

Ive always had cars that had posi units in them so this is new to me.. Factor in that the car has a t56 6 speed with a very high first gear ratio and a 4:10 in the rear and it makes for a very hard launch... so my next question is this...

This car definately was a drag car as some point..I am looking to make this car a pro touring car... 100% on the street but love to drive and handle through winding twisting roads.. is this differential gonna be a handful to drive under those conditions? If so what would be a better choice to have better street manners but still have the toughness? Also, this one seems to be in EXCELLENT condition so what could I get for it if I wanted to sell it off? The rear housing fits perfect under the car and I run a 295 street radial out back on 15 inch wheels.. I have plenty of room to run a 315 tire with an 18 inch rim which I plan on doing in the near future so I think I will keep everything intact but may want to swap out the differential for better street manners... What do you think? and thanks for all of the comments so far.

Mark
TOOFUN

[exwestracer]

Isn't the pinion angle usually pointing up and the engine pointing down. And shouldn't they usually be equal (or close) and opposite?? Say 2 degrees down for the engine and 2 degrees up for the pinion??

David

David,
The way it really should work is for the pinion and trans output shafts to be parallel under full load. That is when the u-joints see their highest strain and most likely failure due to driveline walk.

On a high torque leaf spring car (such as the OP has), you can see as much as 9-10deg of pinion climb if there is no other anti-rotation device (radius rods, Caltracs, etc). If the engine has, say, 3deg down angle, you would want about 6deg down angle on the pinion so it would end up 3deg up under full axle wrap. Make sense?

On a purpose built leaf drag car, we will level the engine (0deg angle) and set the pinion 9-10deg down to achieve the same result but keep the actual angles to a minimum.